Lighting has many applications across a number of industries. Different spectrums serve different purposes that range from illuminating a work environment, to optimize safety, and to printing PCB boards. One application in particular that is experiencing a rise in innovations is horticulture. Artificial lighting has been used to grow plants for decades, but the technology to do so has experienced only minor improvements compared to innovations in all other aspects of horticulture, such as growth mediums, nutrients, and irrigation system. The use of lighting for horticulture is expected to increase dramatically over the coming decades, which. Such an increase may give rise to more advanced technologies that eliminate the follies of the status quo.
Conventional lighting technologies used in horticultural applications have inherent deficiencies based on the technologies incorporated. High intensity discharge lamps (“HID”), produce significant output in terms of lumens, which is light that falls within the spectrum visible to the human eye. However a large proportion of that output falls within the spectral range of infrared, or heat. This heat may be detrimental to growth of plants and requires the use of active fixture ventilation systems paired with Heating Ventilation and Air Conditioning (“HVAC”) systems to manage the heat effectively. Not only do the bulbs themselves produce a large amount of heat, but the ballasts used to maintain the wattage for bulb ignition and operation also produce heat due to hardware inefficiencies. All of this heat output creates environmental control challenges that lead to subpar growth and overuse of water resources to compensate.
Aside from HID lighting, light emitting diode (“LED”) technology has been attempting to gain traction within the horticulture industry for the last decade. The deficiencies associated with LED fixtures are not so much in terms of heat but are in terms of scalable output and canopy penetration. In terms of output scalability, if a certain output is desired, a fixture must contain a sufficient number of diodes to achieve this output. This not only increases the number of failure modes, but increases the cost to the consumer. In terms of penetration, LEDs simply do not produce enough photon flux, typically measured in μmoles/sec/area, to penetrate beyond the upper canopy of plants. Also, since LEDs are a point source light, light distribution is uneven and creates points called “hotspots.” These “hotspots” will have significantly more photon flux than other parts of an area covered by a light, causing uneven growth.
The current standard for commercial HID grow lighting is 1,000 Watts (W) per light. This number is derived from the wattage used to power high pressure sodium (HPS) light bulbs, which are the bulbs used during the flowering phase of growing. This high wattage is necessary to create an arc between the sodium gases that are contained within the arc tube. To keep this high wattage constant, mechanical, or digital ballast must be used. The use of such types of ballasts may create further inefficiencies. These sort of inefficiencies are unsustainable and may have an overall negative impact on society as a whole, whether it be in terms of power usage or in the manufacture and disposal of bulbs. The inefficiencies are the result of reliance on a technology that, as of this writing, is over fifty years old. Although LED technology makes claims to be more efficient, this is not true in many instances. The reality is that to achieve output even close to that of an HID system, the total wattage used by an LED system may be as high as approximately ninety percent of what an HID system uses.
Further, current lighting technologies offer little to no control over spectrum once a bulb is selected and put into use. In terms of HID bulbs, spectrum varies slightly between bulb manufacturers. However, there is one common trend among all of them. The common trend is that large proportions of unusable green and yellow wavelengths. These wavelengths fall approximately within the range 550 nm to 620 nm, and account for seventy to ninety percent of relative energy. In comparison, beneficial blue and red wavelengths produced by HID Bulbs, generally between 450 nm and 650 nm respectively, may account for only fifteen to thirty percent of the relative energy. The spectrum produced by HID bulbs are generally not adjustable, and bulb depreciation may results in the loss of the beneficial wavelengths for growth first, which leads to frequent bulb replacement.
In terms of LED technologies, blue and red wavelengths, approximately 420-480 nm and 640-700 nm respectively, are used exclusively within LED arrays. Although this would seem like the answer to the issues with HID lighting, the lack of a full spectrum introduces new issues. The use of 450 nm blue and 650 nm red provides optimum levels for the production of chlorophylls B and A, respectively. However, although these wavelengths are important, full spectrum lighting remains important for healthy growth due to other sub-processes occurring at the cellular level of plants.
Current lighting technologies have a fixed footprint, i.e., the coverage area is locked in at a shape determined by the shape of the fixture hood for HID lighting and by the shape of the light array with respect to LED lighting. Since present LEDs do not use reflectors, the overall shape of the fixture dictates the footprint. This limits the coverage area and most often leads to wasted output. Currently, the only way to change the coverage area is by raising and lowering the light, which affects the amount of output coming in contact with the plants and photosynthesis by the plants. As the light moves further away, less photon energy penetrates the canopy. Optimum distance from canopy is approximately twelve to eighteen inches, and as of now no light can adjust the footprint while maintaining this optimum height.
Accordingly, current technology do not provide horticultural lights for which power, spectrum, coverage, and other factors may be controlled as a function of time. Because plants go through different growth stages in which each stage benefits from a different light configuration, tailoring a horticultural light to these different stages would result in a highly efficient and optimized system. However, present technology does not perform this dynamic configuration to optimize for differ growth stages because present technology does not monitor and adjust spectrum, power consumption, heat dispersion, moisture, and other variables conducive to growing. Moreover, present technology also do not offer horticultural lights that can be harnessed in tandem to other outputs, such as audible frequency generation that stimulate growth, and the ability to modify coverage area while maintaining uniformity of coverage.